1) Field of the Invention
This invention relates generally to fabrication of semiconductor devices and more particularly to the etching of organic low-k dielectric layers and particularly an etch process for organic low K layers that uses a ammonia based chemistry (e.g., pure ammonia or ammonia with (H2 or N2))
2) Description of the Prior Art
Traditional etch chemistry for the organic low-k material is N2 related chemistry, such a s N2/O2 and H2/H2 etc. The excellent physical profile of the damascene structure can be obtained by N2/H2 chemistry with a lower etch rate, compared to N2/O2 chemistry. However, it is very likely to get a bowing sidewall profiles (e.g., non-vertical sidewalls) by N2/O2 chemistry.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering U.S. Pat. No. 6,071,815 (Kleinhenz et al.) that shows a silicon oxide layer etch that uses HF and ammonia in combination with other gases.
U.S. Pat. No. 5,897,377 (Suzuki) shows a surface treatment etch.
U.S. Pat. No. 5,972,235 (Brigham et al.) shows a low-k etch.
U.S. Pat. No. 6,063,712 (Gilton et al.) teaches an oxide etch using ammonia a fluorine containing compound and a boron containing compound.
However, further improvement is needed to etch organic low-K materials.
It is an object of the present invention to provide a method for etching low-k dielectric layers.
It is an object of the present invention to provide a method for etching low-k dielectric layers that uses an ammonia based chemistry.
It is an object of the present invention to provide a method for etching low-k dielectric layers that uses an pure ammonia or NH3/H2 or NH3/N2 etch gasses plus optionally CO and/or O2.
To accomplish the above objectives, the present invention provides a method which is characterized as follows. An organic low k dielectric layer is formed over a substrate. A resist pattern is formed over the low k dielectric layer. The resist pattern has an opening.
Using the invention""s etch process, the organic low k dielectric layer is etched through the opening in an etch mask. The invention""s etch process comprise a NH3 containing plasma etch (optionally with H2 or N2).
The invention""s NH3 containing plasma etch etches Low k materials unexpectedly well. The invention""s NH3 only etch had a 30 to 80% higher etch rate than conventional N2/H2 etches of low-k materials like Silk(trademark).
Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of instrumentalities and combinations particularly pointed out in the append claims.